The present invention relates to a method of cooling gas-permeable materials having highly temperature-dependent coefficient of thermal conductivity. More particularly, it relates to a method of cooling such materials in a shaft-shaped chamber wherein a loose material is fed in counter stream to a gaseous cooling medium supplied from below downwardly and wherein the stream of the cooling medium is subdivided into two partial streams.
Methods of cooling of the above-mentioned general type are known in the art. In a known method, a loose material which travels from above downwardly in a shaft-shaped chamber in a counter stream to a gaseous cooling medium, advantageously air or inert gas, is pierced by the cooling medium. The cooled cooling medium is normally directed into the lower part of the chamber and the heated cooling medium is withdrawn from the upper part of the chamber. Subsequently, the heated cooling medium can in some cases be cooled, with heat recovery by supplying the same into a heat exchanger, waste-heat boiler, or another cooling device. After this, the cooling medium can be returned into the process by supplying into the lower part of the shaft-shaped chamber.
At present the above-described process, particularly for so-called dry coke cooling, became very important. This development is based upon the consideration that the previously known conventional methods of coke cooling which involve quenching the glowing coke with water in special quenching towers, is extremely unfavorable in the sense of the energy utilization or energy recovery as well as the environment protection. In the conventional water quenching method, the heat which is withdrawn with the quenching water escapes into the surrounding atmosphere without being used. For example, heat is carried away in the form of vapor clouds in the air and/or with the flowing off quenching water. In contrast, when loose materials are cooled by gaseous cooling medium, as described above, a greater part of heat of the glowing coke can be recovered from the cooling medium in a waste-heat boiler or the like. The so-called dry coke cooling is a preferable application area of the present invention which is, however, not limited to the same. It has been recognized however, that the downward movement of the coke to be cooled in the shaft-shaped chamber is characterized by different speeds. Similarly, the gas stream through the cross-section of the chamber is also non-uniform in many cases. Both these phenomena can naturally cause a non-uniform cooling of the coke, and the cooling is performed slower, particularly in the upper part of the chamber.
The German Auslegeschrift No. 2,432,025 describes an arrangement for dry quenching of coke, in which the gaseous cooling medium is supplied in two partial streams into the cooling chamber. One of the partial streams is directed to the bottom of the chamber and particularly to a compact layer located in this region. The second partial stream is supplied through a so-called stream divider into the interior of the chamber and there exits in the region of the central axis to the compact layer. The above-mentioned German reference does not contain any data about special functions and operation to be performed by the second partial stream of the cooling medium or the manner of dividing the partial streams. The arrangement disclosed in this reference pursues the only purpose to provide of a best possible uniform movement of the material to be treated with a best possible uniform division of the cooling medium.